1. Field of the Invention
The present invention relates to a magnetic recording and reproducing apparatus suitable for use as a digital audio tape recorder (hereinafter referred to as a "DAT"), for example.
2. Description of the Prior Art:
FIG. 15 of the accompanying drawings illustrates a conventional DAT including a rotatable drum 407 having magnetic heads, the drum 407 being inclined at an angle to a reference surface (i.e., a chassis surface) which lies perpendicularly to shafts for tape reels. In the DAT, a tape transport path is established as follows: A magnetic tape T unreeled from a supply reel 401 in a tape cassette 400 passes around a guide 402 fixed to a chassis 418, a pin 403 mounted on a tension arm, a guide 404 fixed to the chassis 418, and a vertical guide roller 405, is then angularly adjusted by an upstream inclined guide 406 so as to be wound partly around the rotatable drum 407, and goes around the drum 407. The tape T which has left the drum 407 is angularly adjusted back by a downstream inclined guide 408, goes around a vertical guide roller 409 and a guide 410 fixed to the chassis 418, passes between a capstan 411 and a pinch roller 412 pressed thereagainst and between a swing guide roller 413 and a fixed guide 414, and is finally wound around a takeup reel 415 in the tape cassette 400.
The vertical guide roller 405 and the inclined guide 406 are fixedly mounted on a guide base 416, and the vertical guide roller 409 and the inclined guide 408 are fixedly mounted on a guide base 417. The guide bases 416, 417 are movable in and along guide grooves 419, 420, respectively, defined in the chassis 418 by means of a suitable drive mechanism for pulling the tape T out of the tape cassette 400 and winding the tape T partly around the drum 407.
The guide bases 416, 417 are pressed respectively against stoppers 421, 422 fixed to the chassis 418 for establishing tape loading positions of the vertical guide rollers 405, 409 and the inclined guides 406, 408 with respect to the drum 407, thus defining a highly accurate tape transport path.
When loading the tape T from the tape cassette 400 into the tape recorder with the vertical guide roller 405 and the inclined guide 406 on the guide base 416 and also with the vertical guide roller 409 and the inclined guide 408 on the guide base 417, the tape T tends to move transversely thereof along the inclined guides 406, 408 due to engagement with the inclined guides 406, 408. Insofar as the tape T is loaded at a low speed, the tape T will not be disengaged from the inclined guides 406, 408 because the tape T is transversely limited by flanges on the vertical guide rollers 405, 409. Since the forces tending to move the tape T transversely along the inclined guides 406, 408 increase as the speed at which the tape T is loaded is increased, however, when the tape T is loaded at a high speed, the tape T may be disengaged from the inclined guides 406, 408. Therefore, it has been difficult to rely on highspeed tape loading. Another problem is that the tape limiting flanges of the vertical guide rollers 405, 409 are responsible for damage to the tape T. When the tape T is loaded while being held in contact with the inclined guides 406, 408, the tape T is subjected to different longitudinal tensions across the width thereof, resulting in localized longitudinal stretching of the tape T.
As described above, the tape loading positions of the vertical guide rollers 405, 409 and the inclined guides 406, 408 with respect to the drum 407 for establishing a high-precision tape transport path are determined by pressing the guide bases 416, 407 respectively against the stoppers 421, 422 fixed to the chassis 418. The tape transport path is thus governed by the accuracy of positioning of the guide bases 416, 417. To position the guide bases 416, 417 highly accurately, it is necessary to meet desired levels for the shape and machining accuracy of the guide bases 416, 417 and the stoppers 421, 422 and also for the positional accuracy of the attached stoppers 421, 422 with respect to the chassis 418. Meeting all of these accuracy requirements however involves an increased cost. The tape transport path tends to gradually vary since the positional accuracy of the guide bases 416, 417 is lowered with time.